The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the referenced prior art forms part of the common general knowledge in Australia.
Pneumatic pumps may be used for pumping flowable compositions in hot or chemically and physically aggressive environments. The compositions may be intractable to rotary, piston and diaphragm pumps, or may be environments where motive means such as IC or electric motors cannot be used. The general configuration of such pumps comprises a pressure vessel cyclically transitioned between an intake cycle where compressed air is used to lower the internal pressure of the vessel by venturi effect to draw material in and a discharge cycle where the venturi is stalled or choked to pressurize the vessel and expel the material.
The straightforward general principle of operation must be optimized for the apparatus to be practical. Efficiency may demand that the delivery and/or inlet ports to the pressure vessel are controlled by gates. Control means may control timing of venturi cycle between vacuum and pressure phases, and control operation of any gate on the inlet and outlet. Control means may respond to time or charge mass to optimize cycle volumes.
Conventional configurations of the pressure vessel usually include that the vessel is in the form of a solid of rotation to resist distortion under pressure, locates the material outlet at the lowest point to maximize gravity assistance, and spatially separates the inlet and the outlet. For example, the pressure vessel may comprise a vertical-axis vessel having a conical lower portion and a domed upper portion, wherein the inlet is toward the top of the vessel and the outlet is toward the bottom. In other embodiments a horizontal-axis vessel may comprise a dome-ended cylinder with the inlet and outlet separated both horizontally and vertically.
The prior art apparatus works well for large scale apparatus, but does not appear to scale down well for portable apparatus. In the first instance, the shape of conventional designs does not admit of a compact package. Secondly the size of inlets and outlets (confined by the materials) cannot scale down as far as the size of the pressure vessel by proportions, resulting in volumetric inefficiency.